The metal plating of objects is an important technology in the mounting of electrical and electronic parts, and development has been underway on this front. However, metal plating a difficult-to-plate object such as a mirror-finished object with low conductivity, typified by a semiconductor wafer, still poses technological difficulties, and many different methods have been devised to this end. These methods include one involving a pretreatment in which a silane coupling agent is used on the object to be plated, that is, a silane coupling agent is interposed between the object to be plated and the metal plating film.
The method disclosed in Japanese Patent Publication 7-102380A is an example of interposing a silane coupling agent between the object to be plated and the metal plating film so as to obtain good adhesion. The treatment method disclosed in this document, however, uses a silane coupling agent along with a urethane resin, the silane coupling agent firmly bonds with both the urethane resin and the glass fiber that is the material to be plated, and the urethane resin thus bonded to the glass fiber improves the adhesion of the metal electroless plating film. Also, Japanese Patent Publication 7-102380A states that the object to be plated is treated with the silane coupling agent along with the urethane resin, dried, and then heat treated for 5 minutes at 120° C., and the purpose of this heat treatment is to ensure the bonding of the silane coupling agent to the surface of the object being plated, and the bonding reaction between the urethane resin and the silane coupling agent.
Also, it is stated in Japanese Patent Publication 8-39728A that when the drying temperature is over 150° C. following the surface treatment of the plating object with a silane coupling agent, the silane coupling agent evaporates along with the solvent in the silane coupling agent solution, so there is a variance in the thickness of the silane coupling agent layer. The usual procedure up to now has been to coat with a silane coupling agent, then affix the silane coupling agent to the plating object, so the drying temperature has been 150° C. or under.
In addition, there have been proposed a method involving the use of a pretreatment agent comprising a combination of a special silane coupling agent and a noble metal compound (see the pamphlet of International Patent Publication 01-49898); a method in which the plating object is treated with a pretreatment agent to which a special silane coupling agent and a reducing agent are sequentially added (see the pamphlet of International Patent Publication 01/81652); a method in which the plating object is sequentially treated with a solution containing an alkali metal salt and a special silane coupling agent (see Japanese Patent Publication 2002-226972A); and a pretreatment liquid containing specific proportions of a special silane coupling agent and a noble metal compound (see Japanese Patent Publication 2003-13241A). This prior art is effective in terms of metal-plating materials that are difficult to plate, but in every case the temperature is about 60 to 120° C. in order to dry off the solvent after the silane coupling agent has been applied to the plating object, and no particular study has gone into the heat treatment.                Patent Document 1: Japanese Patent Publication 7-102380A        Patent Document 2: Japanese Patent Publication 8-39728A        Patent Document 3: International Patent Publication 01-49898 pamphlet        Patent Document 4: International Patent Publication 01-81652 pamphlet        Patent Document 5: Japanese Patent Publication 2002-226972A        Patent Document 6: Japanese Patent Publication 2003-13241A        